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1.
In nuclear safeguards, precise and accurate isotopic analyses are needed for two major elements from the nuclear fuel cycle: uranium and plutonium. This can be achieved by Isotope Dilution Mass Spectrometry (IDMS), which is one of the most reliable analytical techniques for the determination of plutonium amount content to a high level of accuracy. In order to achieve reliable isotope measurements isotopic reference materials with certified amount of plutonium and isotopic composition are required. At the Institute for Reference Materials and Measurements (IRMM) various plutonium spike reference materials for isotopes 239Pu, 240Pu, 242Pu and 244Pu are available. This enabled the setup of an inter-calibration campaign inter-linking selected plutonium spikes on a metrological basis applying state-of-the-art measurement procedures. The aim of this campaign is threefold: firstly to perform measurements on selected plutonium spike isotopic reference materials for quality control purposes, secondly to verify the amount content and the isotopic composition of the recently produced IRMM-1027m large sized dried (LSD) spikes and thirdly to demonstrate IRMM’s measurement capabilities for plutonium analysis via external quality tools. The obtained results using various spike isotopic reference materials will be presented and discussed in this paper. The measurement uncertainties of the IDMS results were calculated according to the guide to the expression of uncertainty in measurement (GUM).  相似文献   

2.
A reverse isotope dilution alpha spectrometric /R-IDAS/ method using239Pu as a spike is described for the determination of plutonium concentration in high burn-up fuel samples wth238Pu/(239Pu+240Pu) alpha activity ratio >0.5, without resorting to any purification from241Am and a bulk of other impurities. It involves the addition of a pre-clibrated spike solution to a known aliquot of the plutonium sample solution followed by source preparation using TEG as a spreading agent. The results obtained on a number of plutonium samples containing 20–80% of241Am /alpha activity wise/ using this method are compared with those achieved by R-IDAS using purification with TTA, with respect to precision and accuracy. Precision and accuracy of 0.5% are demonstrated. This method eliminates the need of any separation and purification of plutonium from241Am and a bulk of other impurities like uranium.  相似文献   

3.
Summary A thermal ionization mass spectrometry (TIMS) method is described for the determination of ultra-trace levels of plutonium isotopes in human urine samples. The method has been validated through the analysis of artificial urine samples spiked with known amounts of 239Pu ranging from 2.5 fg to 50 fg (6-115mBq). A slight positive bias of 1.7%-2.7% was determined, with a relative precision of 2.2% at 50 fg, increasing to 2.7% for 5-25 fg 239Pu. The detection limit of the method was 0.53 fg (1.2mBq) 239Pu, and the instrumental detection limit was at least 0.1 fg. The determination of the isotopic signature of the sample with 239Pu, 240Pu, and 241Pu amounts of several femtograms is possible, and was demonstrated with the determination of the 240 to 239 ratio in an inter-laboratory sample comparison. The method is relatively free from interferences, 95% of sample preparations were acceptable both in terms of chemical recovery and lack of isobaric interference. The isotopic abundance of the 242Pu SRM 4334E of the National Institute of Standards and Technology (NIST) was also determined by TIMS and was found to be 99.99967 atom% 242Pu.  相似文献   

4.
The concentrations of238Pu and239, 240Pu were determined in 12 sediment samples collected from the bed of the Romanian Danube river and Black Sea coast during June–September 1994. After the sample material has been properly prepared and242Pu tracer added, plutonium was separated from americium and curium by anion exchange. After electrodeposition on stainless steel discs the elements were counted with an -spectrometry system with silicon surface-barrier detectors. The239, 240Pu concentrations range between 150 and 800 mBq kg–1 dry, while the238Pu concentrations rise up to max 150 mBq kg–1 dry. Although the chemical yields are rather low (51%) we appreciate the results as valuable since they report for the first time the distribution of the plutonium contamination along the Danube river and the Black Sea coast-Romanian sector.  相似文献   

5.
Half-life of241Pu is of great importance in nuclear technology. In view of large variation in the values (13–15 y) reported till 1974 in literature, efforts have been made in different laboratories to determine this half-life with high precision and accuracy. In our laboratory, it has been determined by different methods which may be classified in two categories, viz. (1) parent decay method, and (2) daughter growth method. In the parent decay method, change in isotope ratios241Pu/239Pu,241Pu/240Pu and241Pu/242Pu was studied periodically by a thermal ionization mass spectrometer. Single as well as double ratio method was used to calculate the half-life. In the daughter growth method, the half-life was obtained in four independent ways. These were (1) alpha spectrometry taking239Pu and242Pu separately as reference isotopes and studying periodically the increase in alpha activity ratio, (2) alpha proportional counting for observing periodically the change in total alpha activity, (3) isotope dilution alpha spectrometry using243Am as a spike, (4) isotope dilution mass spectrometry using243Am as a spike. In all these methods, synthetic mixtures were prepared for achieving high precision and accuracy in different measurements. Based on the results obtained in this laboratory and the values reported by other laboratories, a half-life value of 14.4±0.1 y is recommended. The paper reviews the past history, puts forth the present status, highlights the current trends for studying the effect of chemical composition of plutonium on the half-life of241Pu and presents the future requirements for achieving higher accuracy in the half-life of241Pu.  相似文献   

6.
Experimental evaluation on the use of239Pu spike in Isotope Dilution-Thermal Ionization Mass Spectrometry (ID-TIMS),238Pu spike in Isotope Dilution Alpha Spectrometry (IDAS) and233U as a Non-Isotopic Diluent in Alpha Spectrometry (N-IDAS), for determing plutonium concentration in samples with burn-up values in the range of 1,000–10,000 MWD/TU is done. Precision is determined by analyzing replicate aliquots from different samples using each of the three spikes. Accuracy is established by comparing the results with those obtained by using well recognized spike242Pu in ID-TIMS. It is shown that the use of239Pu spike with the latest generation thermal ionization mass spectrometers gives the best precision (0.2%), whereas the precision values of 0.5 and 1% can be obtained by using238Pu and233U spikes, respectively, on a routine basis. Reasons for the difference in the precision values are discussed, along with the merits and drawbacks on the use of different spike isotopes.  相似文献   

7.
A gamma-spectrometric method using an intrinsic high resolution germanium detector has been developed for the determination of isotope ratios of plutonium from samples in solution form. The method is based on the assay of low energy gamma-rays of238Pu,239Pu,240Pu and241Pu and does not require the use of branching intensities or the knowledge of detection efficiencies for different gamma rays. Since low energy gamma-rays are used, the effect of241Am has also been studied. It is found that results are not affected up to 0.5 wt% of241Am in plutonium samples. An accuracy of 3% is achievable in the determination of240Pu/239Pu and241Pu/239Pu atom ratios as demonstrated by carrying out measurements on isotopic standards of plutonium.  相似文献   

8.
Summary A method is described for determining the plutonium concentration by Isotope Dilution Alpha Spectrometry (IDAS) using238Pu as a spike. It involves the addition of a pre-calibrated spike solution to a known aliquot of the plutonium sample solution followed by source preparation using TEG as a spreading agent. The results obtained on a number of samples using this method are compared with those of IDMS using242Pu as a spike as well as with those obtained by IDAS using TTA for purification, with respect to precision and accuracy. Precision of 0.3–0.5% and an accuracy of 0.5% is demonstrated. This method eliminates the need of any separation and purification of plutonium from241 Am and a bulk of other impurities.
Plutoniumbestimmung durch Isotopenverdünnungs-Alpha-Spektrometrie ohne Abtrennung von Americium-241 und anderen Verunreinigungen
Zusammenfassung Bei dem beschriebenen Verfahren der Isotopenverdünnungs-Alpha-Spektrometrie (IDAS) wird238Pu als Spike benutzt. Eine vorgeeichte Spike-Lösung wird zu einem bekannten Aliquot der Probe gegeben und anschließend die Strahlungsquelle unter Verwendung von Tetraethylenglykol als Spreading-Reagens vorbereitet. Die nach diesem Verfahren erhaltenen Ergebnisse werden in bezug auf Präzision und Genauigkeit mit solchen verglichen, die mit Isotopenverdünnungs-Massenspektrometrie unter Verwendung von242Pu als Spike oder mit IDAS unter Verwendung von Thenoyltrifluoraceton zur Reinigung erhalten wurden. Eine Präzision von 0,3–0,5% und eine Genauigkeit von 0,5% wurden erzielt. Durch das beschriebene Verfahren erübrigt sich eine Reinigung des Pu von241Am und anderen Verunreinigungen.
  相似文献   

9.
A radiochemical procedure is described for the simultaneous determination of238Pu,239+240Pu,241Pu,241Am,242Cm,244Cm,89Sr, and90Sr in vegetation samples. The method was applied for the determination of these, radionuclides in grass, collected near Munich after the fallout from the reactor accident at Chernobyl, USSR. The specific activities observed were (in Bq kg–1 dry weight):238Pu, 0.077;239+240Pu, 0.15;241Pu, 3.9;241Am, 0.031;242Cm, 3.0;244Cm, 0.008;89Sr, 2000;90Sr, 99.  相似文献   

10.
A radiochemical method has been developed for the determination of238Pu,239, 240Pu,241Am,242Cm and244Cm in airborne effluents of nuclear power plants. The method involves conversion of transuranium elements to acid-soluble forms, dissolution, purification, electrodeposition and alpha spectrometric determination. Final recovery ranged from 69.0 to 75.4% for plutonium and from 26.8 to 68.3% for americium and curium.  相似文献   

11.
Transuranium nuclides were produced by irradiating a pellet of natural uranium sulfide in the Japan Material Testing Reactor (JMTR). After irradiation, a successive separation of uranium, plutonium, americium and curium was carried out. The fractional concentrations of the nuclides238Pu,239Pu,240Pu,241Am,243Am,242Cm and244Cm were determined by α-ray spectrometry, and those of241Pu and242mAm were estimated from the build-up of α-emitting daughters,241Am and242Cm, respectively. As the yield of242Pu was too slight to be detected by α-counting, the neutron activation analysis of the plutonium fraction based on the242Pu(n, γ)243Pu reaction was carried out by γ-ray spectrometry, and it was shown that a few pg of242Pu could be determined. A burn-up of235U was also estimated by neutron activation analysis. The experimental results are compared with the calculated ones.  相似文献   

12.
The Standard Reference Material 4351 from the National Institute of Standards and Technology is acknowledged to be inhomogeneous. The value of a single analysis for239Pu+240Pu could lie within a wide range, but the accuracy of the analysis can be corroborated by comparing the corresponding238Pu/239Pu+240Pu or240Pu/239Pu values with the relationships between these ratios and the total plutonium concentration.  相似文献   

13.
Oxygen and ammonia were evaluated as reaction gases for the chemical separation between uranium and plutonium in the bandpass reaction cell or dynamic reaction cell (DRC) of the ELAN DRC II mass spectrometer. Both uranium and plutonium demonstrated similar reactivity with oxygen giving rise to corresponding oxides. At the same time, remarkable selectivity in the reaction with ammonia was observed. While uranium was rapidly converted into UNH 2+ and UN2H 4+ , plutonium remained unreactive in the DRC pressurized with ammonia. This difference in the reactivity allowed the determination of plutonium isotopes in urine and water samples containing excess uranium without preceding separation procedure. Detection limits of 0.245, 0.092, 0.270 and 0.237 ng L–1 were obtained for 238Pu, 239Pu, 240Pu and 242Pu, respectively, in urine spiked with 10 g L–1 of U.  相似文献   

14.
Concentrations of239+249Pu in environmental samples were detemined by ICP-MS and spectrometry, showing consistent results, which suggests an applicability of ICP-MS to239Pu and240Pu measurement. The activity ratios of238Pu/239+240Pu and240Pu/239Pu were significantly different in samples from the general environment and near Sellafield reprocessing plants, indicating the usefulness of these ratios for identification of the Pu contamination source.  相似文献   

15.
Plutonium isotopic ratios have been calculated in soils contaminated by the Palomares accident which occurred in 1966 (Almería, Southeastem Spain). Contrasted techniques have been used to determine the radionuclide activities:238Pu and238+240Pu were analysed by -spectrometry prior purification on anion-exchange resins, the ratio239Pu/240Pu was estimated by -spectra deconvolution and241Pu was directly measured by liquid scintillation counting and indirectly through quantification of in-grown241Am from aged plutonium discs. The mean activity ratios238Pu/239Pu,239Pu/240Pu,241Pu/239Pu, backdated to 1966, were 0.027±0.002 (1), 4.5±0.2 (1) and 8.2±0.8 (1), respectively, characterizing the accident of Palomares as the source term of the measured plutonium.  相似文献   

16.
239+240Pu and-when possible-also the ratio238Pu/239+240Pu was determined in the lungs and livers of 15 residents from Chernobyl-fallout contaminated areas in Byelorussia. In several cases various sections of the lungs were analyzed separately. With the exception of one person the activity concentrations of239+240Pu, were always within the range expected from the global fallout of weapon tests in the sixties and did not indicate any contribution of Chernobyl-derived plutonium.  相似文献   

17.
We have developed an analytical method for detection of239Pu in aqueous samples at concentrations as low as 10–10M. This nuclear counting technique utilizes the uranium L X-rays, which follow the alpha-decay of plutonium. Because L X-rays are specific for the element and not for the individual isotope, the isotopic composition of the plutonium sample must be known. The counting efficiency in the 11–23 keV range is determined from a plutonium standard, and the concentration of the sample is then calculated from the L X-ray count and the isotopic composition. The total L X-ray count is corrected for possible contributions from other radionuclides present as impurities by measuring the low-energy gamma-spectrum for each contaminant to establish specific photon/X-ray ratios. The ratios are important when241Pu and242Pu are measured, because the respective decay chain members produce non-U L X-rays. This new method can replace the use of labor-intensive radiochemical separation techniques and elaborate activation methods for analysis of239Pu in aqueous samples. It is also applicable for assaying plutonium in liquid wastes that pose possible hazards to the environment.  相似文献   

18.
Actinide elements concentrations in the products of near release from CNPP accident were estimated. The data on uranium,237Np,241Am and plutonium and curium isotopes content in fuel particles are given. Sums of -emitting radionuclides and plutonium isotopes in reactor graphite particles and of uranium,242Cm,239+240Pu isotopes in the soil and aerosol samples were also determined. By 1989 soil and dust contamination in near release of the accident is due to long-lived -emitting plutonium isotopes.  相似文献   

19.
The methods available for determination of environmental contamination by plutonium at ultra-trace levels require labor-consuming sample preparation including matrix removal and plutonium extraction in both nuclear spectroscopy and mass spectrometry. In this work, laser-ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) was applied for direct analysis of Pu in soil and sediment samples. Application of a LINA-Spark-Atomizer system (a modified laser ablation system providing high ablation rates) coupled with a sector-field ICP–MS resulted in detection limits as low as 3×10–13 g g–1 for Pu isotopes in soil samples containing uranium at a concentration of a few g g–1. The isotope dilution (ID) technique was used for quantification, which compensated for matrix effects in LA–ICP–MS. Interferences by UH+ and PbO2+ ions and by the peak tail of 238U+ ions were reduced or separated by use of dry plasma conditions and a mass resolution of 4000, respectively. No other effects affecting measurement accuracy, except sample inhomogeneity, were revealed. Comparison of results obtained for three contaminated soil samples by use of -spectrometry, ICP–MS with sample decomposition, and LA–ICP–IDMS showed, in general, satisfactory agreement of the different methods. The specific activity of 239+240Pu (9.8±3.0 mBq g–1) calculated from LA–ICP–IDMS analysis of SRM NIST 4357 coincided well with the certified value of 10.4±0.2 mBq g–1. However, the precision of LA–ICP–MS for determination of plutonium in inhomogeneous samples, i.e. if "hot" particles are present, is limited. As far as we are aware this paper reports the lowest detection limits and element concentrations yet measured in direct LA–ICP–MS analysis of environmental samples.Sergei F. Boulyga is on leave from The Radiation Physics and Chemistry Problems Institute, 220109 Sosny, Minsk, Belarus.  相似文献   

20.
Among the transuranic elements present in the environment, plutonium isotopes are mainly attached to particles, and therefore they present a great interest for the study and modelling of particle transport in the marine environment. Except in the close vicinity of industrial sources, plutonium concentration in marine sediments is very low (from 10−4 ng kg−1 for 241Pu to 10 ng kg−1 for 239Pu), and therefore the measurement of 238Pu, 239Pu, 240Pu, 241Pu and 242Pu in sediments at such concentration level requires the use of very sensitive techniques. Moreover, sediment matrix contains huge amounts of mineral species, uranium and organic substances that must be removed before the determination of plutonium isotopes. Hence, an efficient sample preparation step is necessary prior to analysis. Within this work, a chemical procedure for the extraction, purification and pre-concentration of plutonium from marine sediments prior to sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) analysis has been optimized. The analytical method developed yields a pre-concentrated solution of plutonium from which 238U and 241Am have been removed, and which is suitable for the direct and simultaneous measurement of 239Pu, 240Pu, 241Pu and 242Pu by SF-ICP-MS.  相似文献   

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